This research project involves an intensive quantitative study of a small (30-celled) integrative system, the stomatogastric ganglion of the spiny lobster. A detailed quantitative study is being conducted of: 1) activity patterns produced and their reaction to perturbations; 2) repetitive firing properties (pacemaker sensitivity, adaptation, rebound, reaction to pertubations as a function of phase in firing cycle) of each individual neuron type; 3) special cellular properties (plateau-potential production; delaying conductances) of each neuron; 4) synaptic interactions (PSP shape, physiological effectiveness, reversal potential and facilitation effects, electrotonic and "chemotonic" (D.C. chemical) interactions) for all interacting pairs. 5) The principal goals of this will be production of a series of physiologically reliable computer models of the system. As more quantitative data become available, progressively more accurate models will be produced. The models in turn will be used as a means for confirming or rejecting theories on pattern production in the ganglion; for uncovering additional factors in the ganglion that are contributory to its physiological properties; and for investigating the stability of patterns to parameter variation to gain insight into why physiological properties are set as they are.